|
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH] libxl: new xlu_disk_parse function
From: Ian Jackson <ijackson@xxxxxxxxxxxxxxxxxxxxxx>
Introduce new flex/regexp-based parser for disk configuration strings.
Callers will be updated in following patches.
Signed-off-by: Ian Jackson <ijackson@xxxxxxxxxxxxxxxxxxxxxx>
---
config/StdGNU.mk | 1 +
tools/libxl/Makefile | 9 +-
tools/libxl/libxlu_cfg.c | 42 +++++++---
tools/libxl/libxlu_disk.c | 164 +++++++++++++++++++++++++++++++++++++++++
tools/libxl/libxlu_disk_i.h | 19 +++++
tools/libxl/libxlu_disk_l.l | 54 ++++++++++++++
tools/libxl/libxlu_internal.h | 20 +++++
tools/libxl/libxlutil.h | 12 +++
8 files changed, 304 insertions(+), 17 deletions(-)
create mode 100644 tools/libxl/libxlu_disk.c
create mode 100644 tools/libxl/libxlu_disk_i.h
create mode 100644 tools/libxl/libxlu_disk_l.l
diff --git a/config/StdGNU.mk b/config/StdGNU.mk
index 25aeb4d..9b331f0 100644
--- a/config/StdGNU.mk
+++ b/config/StdGNU.mk
@@ -67,6 +67,7 @@ CURSES_LIBS = -lncurses
PTHREAD_LIBS = -lpthread
UTIL_LIBS = -lutil
DLOPEN_LIBS = -ldl
+PCRE_LIBS = -lpcre
SONAME_LDFLAG = -soname
SHLIB_LDFLAGS = -shared
diff --git a/tools/libxl/Makefile b/tools/libxl/Makefile
index a7b1d51..f0c473f 100644
--- a/tools/libxl/Makefile
+++ b/tools/libxl/Makefile
@@ -22,7 +22,7 @@ endif
LIBXL_LIBS =
LIBXL_LIBS = $(LDLIBS_libxenctrl) $(LDLIBS_libxenguest) $(LDLIBS_libxenstore)
$(LDLIBS_libblktapctl) $(UTIL_LIBS) $(LIBUUID_LIBS)
-LIBXLU_LIBS =
+LIBXLU_LIBS = $(PCRE_LIBS)
LIBXL_OBJS-y = osdeps.o libxl_paths.o libxl_bootloader.o flexarray.o
ifeq ($(LIBXL_BLKTAP),y)
@@ -38,9 +38,10 @@ LIBXL_OBJS = flexarray.o libxl.o libxl_create.o libxl_dm.o
libxl_pci.o \
libxl_internal.o libxl_utils.o $(LIBXL_OBJS-y)
LIBXL_OBJS += _libxl_types.o
-AUTOINCS= libxlu_cfg_y.h libxlu_cfg_l.h
-AUTOSRCS= libxlu_cfg_y.c libxlu_cfg_l.c
-LIBXLU_OBJS = libxlu_cfg_y.o libxlu_cfg_l.o libxlu_cfg.o
+AUTOINCS= libxlu_cfg_y.h libxlu_cfg_l.h libxlu_disk_l.h
+AUTOSRCS= libxlu_cfg_y.c libxlu_cfg_l.c libxlu_disk_l.c
+LIBXLU_OBJS = libxlu_cfg_y.o libxlu_cfg_l.o libxlu_cfg.o \
+ libxlu_disk_l.o libxlu_disk.o
CLIENTS = xl
diff --git a/tools/libxl/libxlu_cfg.c b/tools/libxl/libxlu_cfg.c
index f947c21..fd3e102 100644
--- a/tools/libxl/libxlu_cfg.c
+++ b/tools/libxl/libxlu_cfg.c
@@ -15,6 +15,7 @@ XLU_Config *xlu_cfg_init(FILE *report, const char
*report_filename) {
if (!cfg->filename) { free(cfg); return 0; }
cfg->settings= 0;
+ cfg->disk_re= 0;
return cfg;
}
@@ -38,6 +39,29 @@ static int ctx_prep(CfgParseContext *ctx, XLU_Config *cfg) {
static void ctx_dispose(CfgParseContext *ctx) {
if (ctx->scanner) xlu__cfg_yylex_destroy(ctx->scanner);
+ if (ctx->disk_re) pcre_free(ctx->disk_re);
+}
+
+int xlu__scanner_string_prep(CfgParseContext *ctx, YY_BUFFER_STATE *buf,
+ XLU_Config *cfg, const char *data, int length) {
+ int e;
+
+ e= ctx_prep(ctx, cfg);
+ if (e) return e;
+
+ *buf = xlu__cfg_yy_scan_bytes(data, length, ctx->scanner);
+ if (!*buf) {
+ fprintf(cfg->report,"%s: unable to allocate scanner buffer\n",
+ cfg->filename);
+ return ENOMEM;
+ }
+
+ return 0;
+}
+
+void xlu__scanner_string_dispose(CfgParseContext *ctx, YY_BUFFER_STATE *buf) {
+ if (*buf) xlu__cfg_yy_delete_buffer(*buf, ctx->scanner);
+ ctx_dispose(ctx);
}
static void parse(CfgParseContext *ctx) {
@@ -87,25 +111,17 @@ int xlu_cfg_readfile(XLU_Config *cfg, const char
*real_filename) {
int xlu_cfg_readdata(XLU_Config *cfg, const char *data, int length) {
int e;
- YY_BUFFER_STATE buf= 0;
-
+ YY_BUFFER_STATE buf=0;
CfgParseContext ctx;
- e= ctx_prep(&ctx, cfg);
- if (e) { ctx.err= e; goto xe; }
+ ctx.scanner=0;
- buf = xlu__cfg_yy_scan_bytes(data, length, ctx.scanner);
- if (!buf) {
- fprintf(cfg->report,"%s: unable to allocate scanner buffer\n",
- cfg->filename);
- ctx.err= ENOMEM;
- goto xe;
- }
+ e = xlu__scanner_string_prep(&ctx,&buf, cfg,data,length);
+ if (e) { ctx.err = e; goto xe; }
parse(&ctx);
xe:
- if (buf) xlu__cfg_yy_delete_buffer(buf, ctx.scanner);
- ctx_dispose(&ctx);
+ xlu__scanner_string_dispose(&ctx,&buf);
return ctx.err;
}
diff --git a/tools/libxl/libxlu_disk.c b/tools/libxl/libxlu_disk.c
new file mode 100644
index 0000000..be523f7
--- /dev/null
+++ b/tools/libxl/libxlu_disk.c
@@ -0,0 +1,164 @@
+
+/* Parsing the disk spec a tricky problem, because the target
+ * string might contain "," which is the delimiter we use for
+ * stripping off things on the RHS, and ":", which is the delimiter
+ * we use for stripping off things on the LHS.
+ *
+ * For the LHS we use a flex scanner, see libxlu_disk_l.l.
+ * That chops prefixes like "phy:" from the front of the string,
+ * accumulating information into the disk structure.
+ *
+ * For the RHS, we use a regexp using pcre.
+ */
+
+#include "libxlu_internal.h"
+#include "libxlu_disk_l.h"
+#include "libxlu_disk_i.h"
+#include "libxlu_cfg_i.h"
+
+static void err_core(DiskParseContext *dpc, const char *message,
+ const char *in, int inlen) {
+ fprintf(dpc->ctx.cfg->report,
+ "%s: config parsing error in disk specification:"
+ " %s: near `%s' in `%.*s'\n",
+ dpc->ctx.cfg->filename, message, dpc->spec, inlen, in);
+ if (!dpc->ctx.err) dpc->ctx.err= EINVAL;
+}
+
+void xlu__disk_err(DiskParseContext *dpc, const char *message) {
+ err_core(dpc, message,
+ xlu__disk_yyget_text(dpc->ctx.scanner),
+ xlu__disk_yyget_leng(dpc->ctx.scanner));
+}
+
+void xlu__disk_rhs(DiskParseContext *dpc) {
+
+ /* variables used by pcre */
+#define WORKSPACE_SIZE 20 /* wtf no manifest constant from pcre */
+#define OVECTOR_SIZE 10
+ int ovector[OVECTOR_SIZE];
+ int workspace[WORKSPACE_SIZE];
+
+ int rc, len;
+ const char *text;
+ libxl_device_disk *disk = dpc->disk;
+
+ static const char *re_text=
+ "(.*),(?:/dev/)?([0-9a-zA-Z]*)(:[0-9a-z]+)?(,[0-9a-z]*)?"
+ /* 1:target 2:vdev 3:type 4:attrib (r/w) */;
+
+ /* compile the regexp if we haven't got one already */
+ if (!dpc->ctx.disk_re) {
+ const char *re_errstr;
+ int re_errcode, re_erroffset;
+
+ dpc->ctx.disk_re = pcre_compile2(re_text, PCRE_DOTALL,
+ &re_errcode, &re_errstr, &re_erroffset,
+ 0);
+ if (!dpc->ctx.disk_re) {
+ if (re_errcode == 21 /* wtf, no manifest constant */) {
+ dpc->ctx.err = ENOMEM;
+ return;
+ }
+ fprintf(dpc->ctx.cfg->report, "config parsing:"
+ " unable to compile regexp: %s [%d] (at `%s')",
+ re_errstr, re_errcode, re_text+re_erroffset);
+ dpc->ctx.err = EIO;
+ return;
+ }
+ }
+
+ /* actually run the regexp match */
+
+ text = xlu__disk_yyget_text(dpc->ctx.scanner);
+ len = xlu__disk_yyget_leng(dpc->ctx.scanner);
+
+ rc = pcre_dfa_exec(dpc->ctx.disk_re, 0,
+ text, len, 0,
+ PCRE_ANCHORED,
+ ovector, OVECTOR_SIZE,
+ workspace, WORKSPACE_SIZE);
+ switch (rc) {
+ case PCRE_ERROR_NOMATCH:
+ xlu__disk_err(dpc, "bad syntax for target, or missing vdev");
+ return;
+ case 2:
+ case 3:
+ case 4:
+ break;
+ default:
+ abort();
+ }
+
+ /* macros for processing info from capturing parens; see pcreapi(3) */
+
+#define CAPTURED(cap) (START((cap)) >= 0)
+#define START(cap) (ovector[(cap)*2])
+#define END(cap) (ovector[(cap)*2+1])
+#define LEN(cap) (END((cap)) - START((cap)))
+#define TEXT(cap) (text + START((cap)))
+
+#define STORE(cap, member) do{ \
+ assert(CAPTURED((cap))); \
+ free(disk->member); \
+ disk->member = malloc(LEN((cap)) + 1); \
+ if (!disk->member) { dpc->ctx.err = ENOMEM; return; } \
+ memcpy(disk->member, TEXT((cap)), LEN((cap))); \
+ disk->member[LEN((cap))] = 0; \
+}while(0)
+
+#define EXACTLY(cap, string) \
+ (CAPTURED((cap)) && \
+ LEN((cap))==strlen((string)) && \
+ !memcmp(TEXT((cap)), (string), LEN((cap))))
+
+#define ERR(cap, msg) \
+ err_core(dpc, (msg), TEXT((cap)), LEN((cap)))
+
+ /* actually process the four capturing parens in our regexp */
+
+ STORE(1, pdev_path);
+
+ STORE(2, vdev);
+
+ if (!CAPTURED(3) || EXACTLY(3, ":")) {
+ disk->is_cdrom = 0;
+ } else if (EXACTLY(3, ":cdrom")) {
+ disk->is_cdrom = 1;
+ } else {
+ ERR(3, "unknown type (only `:' and `:cdrom' supported)");
+ }
+
+ if (!CAPTURED(4) || EXACTLY(4, ",w") || EXACTLY(4, ",")) {
+ disk->readwrite = 1;
+ } else if (EXACTLY(4, ",r")) {
+ disk->readwrite = 0;
+ } else {
+ ERR(4, "unknown read/write attribute");
+ }
+}
+
+int xlu_disk_parse(XLU_Config *cfg, const char *spec,
+ libxl_device_disk *disk) {
+ YY_BUFFER_STATE buf = 0;
+ DiskParseContext dpc;
+ int e, r;
+
+ dpc.disk = disk;
+ dpc.spec = spec;
+ dpc.ctx.scanner = 0;
+
+ e = xlu__scanner_string_prep(&dpc.ctx,&buf, cfg,spec,strlen(spec));
+ if (e) { dpc.ctx.err = e; goto xe; }
+
+ r = xlu__disk_yylex(dpc.ctx.scanner);
+ if (r) assert(dpc.ctx.err);
+ if (dpc.ctx.err) goto xe;
+
+ if (disk->format == DISK_FORMAT_UNKNOWN) disk->format = DISK_FORMAT_RAW;
+
+ xe:
+ xlu__scanner_string_dispose(&dpc.ctx,&buf);
+ return dpc.ctx.err;
+}
+
diff --git a/tools/libxl/libxlu_disk_i.h b/tools/libxl/libxlu_disk_i.h
new file mode 100644
index 0000000..deb429f
--- /dev/null
+++ b/tools/libxl/libxlu_disk_i.h
@@ -0,0 +1,19 @@
+#ifndef LIBXLU_DISK_I_H
+#define LIBXLU_DISK_I_H
+
+#include "libxlu_internal.h"
+#include "libxl_internal.h"
+
+
+typedef struct {
+ CfgParseContext ctx;
+ const char *spec;
+ libxl_device_disk *disk;
+} DiskParseContext;
+
+void xlu__disk_err(DiskParseContext *dpc, const char *message);
+
+void xlu__disk_rhs(DiskParseContext *dpc);
+
+
+#endif /*LIBXLU_DISK_I_H*/
diff --git a/tools/libxl/libxlu_disk_l.l b/tools/libxl/libxlu_disk_l.l
new file mode 100644
index 0000000..82e2248
--- /dev/null
+++ b/tools/libxl/libxlu_disk_l.l
@@ -0,0 +1,54 @@
+/* -*- fundamental -*- */
+
+%{
+#include "libxlu_disk_i.h"
+
+#define dpc ((DiskParseContext*)yyextra)
+#define YY_NO_INPUT
+
+#define DSET(member,enumname,valname) do{ \
+ if (dpc->disk->member != DISK_##enumname##_UNKNOWN && \
+ dpc->disk->member != DISK_##enumname##_##valname) { \
+ xlu__disk_err(dpc, TOSTRING(member) " respecified"); \
+ return 0; \
+ } else { \
+ dpc->disk->member = DISK_##enumname##_##valname; \
+ } \
+ }while(0)
+
+/* Some versions of flex have a bug (Fedora bugzilla 612465) which causes
+ * it to fail to declare these functions, which it defines. So declare
+ * them ourselves. Hopefully we won't have to simultaneously support
+ * a flex version which declares these differently somehow. */
+int xlu__disk_yyget_column(yyscan_t yyscanner);
+void xlu__disk_yyset_column(int column_no, yyscan_t yyscanner);
+
+%}
+
+%option warn
+%option nodefault
+%option batch
+%option 8bit
+%option noyywrap
+%option reentrant
+%option prefix="xlu__disk_yy"
+%option nounput
+
+%%
+
+raw: { DSET(format,FORMAT,RAW); }
+qcow: { DSET(format,FORMAT,QCOW); }
+qcow2: { DSET(format,FORMAT,QCOW2); }
+vhd: { DSET(format,FORMAT,QCOW2); }
+
+phy: { DSET(format,FORMAT,RAW); DSET(backend,BACKEND,PHY); }
+file: { DSET(format,FORMAT,RAW); DSET(backend,BACKEND,TAP); }
+tapdisk:|tap2?: { DSET(backend,BACKEND,TAP); }
+aio: { }
+ioemu: { }
+
+[a-z][a-z0-9-]*: { xlu__disk_err(dpc,"unknown disk format/method"); return 0; }
+
+[^:]*(\/.*)? { xlu__disk_rhs(dpc); return 0; }
+
+.* { xlu__disk_err(dpc,"bad disk syntax"); return 0; }
diff --git a/tools/libxl/libxlu_internal.h b/tools/libxl/libxlu_internal.h
index e251a63..d681fba 100644
--- a/tools/libxl/libxlu_internal.h
+++ b/tools/libxl/libxlu_internal.h
@@ -21,10 +21,15 @@
#include <string.h>
#include <assert.h>
+#include <pcre.h>
+
#define XLU_ConfigList XLU_ConfigSetting
#include "libxlutil.h"
+
+
+
struct XLU_ConfigSetting { /* transparent */
struct XLU_ConfigSetting *next;
char *name;
@@ -37,12 +42,27 @@ struct XLU_Config {
XLU_ConfigSetting *settings;
FILE *report;
char *filename;
+ pcre *disk_re;
};
typedef struct {
XLU_Config *cfg;
int err, lexerrlineno, likely_python;
void *scanner;
+ pcre *disk_re;
} CfgParseContext;
+
+#ifndef YY_TYPEDEF_YY_BUFFER_STATE
+#define YY_TYPEDEF_YY_BUFFER_STATE
+typedef struct yy_buffer_state *YY_BUFFER_STATE;
+#endif
+
+int xlu__scanner_string_prep(CfgParseContext *ctx, YY_BUFFER_STATE *buf,
+ XLU_Config *cfg, const char *data, int length);
+ /* Caller must initialise ctx->scanner=0 and buf=0 beforehand. */
+
+void xlu__scanner_string_dispose(CfgParseContext *ctx, YY_BUFFER_STATE *buf);
+
+
#endif /*LIBXLU_INTERNAL_H*/
diff --git a/tools/libxl/libxlutil.h b/tools/libxl/libxlutil.h
index 8a6fcbd..acf96fd 100644
--- a/tools/libxl/libxlutil.h
+++ b/tools/libxl/libxlutil.h
@@ -58,4 +58,16 @@ const char *xlu_cfg_get_listitem(const XLU_ConfigList*, int
entry);
/* xlu_cfg_get_listitem cannot fail, except that if entry is
* out of range it returns 0 (not setting errno) */
+
+/*
+ * Disk specification parsing.
+ */
+
+int xlu_disk_parse(XLU_Config *cfg, const char *spec,
+ libxl_device_disk *disk);
+ /* disk must have been initialised; on error, returns errno value;
+ * bad strings, returns EINVAL and prints a message to cfg's report.
+ * That's all cfg is used for. */
+
+
#endif /* LIBXLUTIL_H */
--
1.5.6.5
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel
|
 |
Lists.xenproject.org is hosted with RackSpace, monitoring our |